<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        #joker{
            width: 200px;
            height: 200px;
            background-color: brown;
            animation: bianse 5s;
        }
        @keyframes bianse{
            0%{
                background-color: brown;
            }
            50%{
                background-color: aquamarine;
            }
            100%{
                background-color: brown;
            }
        }
    </style>
</head>
<body>
    <div id="joker"></div>
</body>
</html>